Wild Wild Technologies

2011年10月21日 星期五

15 video clips are widely spreading over the Internet, of 10 to 20 minutes long each, capturing divers from the Beijing Olympic Games practicing in “Water Cube”. What makes it special is that it sees-through the divers’ swimsuits, resulting in a picture of the decades of both male and female athletes hang around naked.

Very few is known about who was capturing the video, and how. Communities from the Internet reproves the act, stating that it is an infringement on privacy, and urging the police to investigate, and to stop these things from happen again. But before the police does their jobs, how can the others protect themselves? We gonna be familiar with how the see-through thing works.

It is infra-red

You likely have heard about infra-red. In fact, it is a mature technology that is widely used in our daily life. Your TV remote control probably has an infra-red light bulb in front of it. It sends signals to the TV receiver, to tell the TV to turn on/off, or to change channels. “But I can’t see the light?” you said. Well, it is because infra-red is invisible. To be precise, let’s rephrase it to: our eyes cannot see infra-red.

In order to make see-through works, one must separate the visible light entering the camera lens from infra-red light. One common way to do it is to use IR-through filters. A better way is to use computer software to filter out the visible light from the raw data collected by the camera's CCD; the advantage of using software is that it can do an optimal cut, resulting in much clearer pictures. The down-side of the software approach is that you cannot reprogram a digital camera; it only works on customized (programable) devices.

Does it work with web cams/my phone’s camera?

Yes. And in fact, they do better. It is a common misconception that expensive cameras give better IR images. They do not. Because of the smaller form factors, web cams and phone cameras have thinner IR-cut filters and let go more infra-red. Web cams may be limited by their resolutions, but phone cameras do a great job!

To say the 2011 Veolia World Solar Challenge — a 1,900 mile race for solar powered cars across the center of Australia from Darwin in the north to Adelaide in the south — has been an explosive event is not only true, but something of an understatement.

The winner, Team Tokai from Japan, crossed the finish line after a 32 hour, 45 minute journey in their car Tokai Challenger 2. They were followed by a close second place Nuon team from the Netherlands, who drew a time of 33.5 hours.

image via World Solar Challenge

Even for the winners this race, from the beginning, has been a grueling one. On Sunday October 16, 42 teams from 21 countries took to the starting line in Darwin. Everyone must have known how difficult this race was going to be. After all, the Australian outback is a brutal, unforgiving landscape and 1,900 miles is a long way. But the race rules haven’t made the job any easier. The event is conducted in a single stage from Darwin to Adelaide and all teams must be fully self-sufficient. During the journey there are seven mandatory check points where observers are changed and team managers may update themselves with the latest information on the weather and their own position in the field. Here teams may perform the most basic of maintenance only – checking and maintenance of tire pressure and cleaning of debris from the vehicle.

As the race revved up toward its conclusion, no one could have imagined how tough it was going to be. On day two, according to race organizers, the three leading teams, Tokai, Nuon and the University of Michigan, were forced to call stop at Wauchope after police closed the route in both directions due to arson fires raging in the desert and burning across the highway.

Day three was just another day in the outback. The sun beat down as usual, but wind gusts kicked up dust devils and made handling the low-slung, winged vehicles a chore to pilot. As if that wasn’t enough, the vehicle of Team Philippines began to overheat just after its team had called it a day. The battery pack generated enough heat to set the car on fire. Fortunately, the fire was extinguished and the crew was able to get the vehicle moving again.

2011年7月15日 星期五

"Acoustic metamaterial" may sound exotic, but researchers in France have managed to assemble one from a few multipacks of cola cans. Arranged in a grid, the drinks cans act as a superlens for sound, focusing acoustic waves into much smaller regions than their metre-long wavelengths typically allow. The cans act as resonators, directing the volume of the sound to peak in a space just a few centimetres wide, and this heightened precision could improve acoustic-actuator systems.

Propagating light or sound waves diffract when they encounter an object, with the resulting interference preventing the waves from being focused to a spot smaller than about half their wavelength. However, the scattering process also involves evanescent waves, which prevent discontinuities in the electromagnetic field and fade away quickly – within half a wavelength of the reflecting object.

Superlenses pick up and amplify these evanescent waves and offer a way of beating the diffraction limit. Now, Geoffroy Lerosey, Fabrice Lemoult and Mathias Fink of the Institute Langevin in Paris have developed a system to build and control evanescent waves in order to tightly focus acoustic energy.

Collective resonance

Each can resonates at about 420 Hz, which is slightly below the standard concert tuning pitch of A above middle C. However, by assembling 49 cans into a seven-by-seven square, the cans resonate collectively rather than individually. By playing a single tone using different combinations of the eight speakers surrounding the array of cans, the researchers are able to make the cans resonate at frequencies of about 340–420 Hz. These resonances are the evanescent waves building up among the cans.

The different resonances produced different shapes in the pressure distribution across the array, measured with a microphone suspended above the cans. Once the researchers had recorded the 49 pressure distributions, or resonant modes, they were able to devise ways to layer the resonances so that these built up in some places and cancelled out in others.

The team managed this through time reversal, a method that owes much to Fink's work since the early 1990s. The researchers choose a can that will host the focused sound and imagine that sound travelling from it to each of the speakers. The team then plays time-reversed versions of these hypothetical waves through the speakers, and the sound naturally builds on itself at the chosen can and cancels out elsewhere. "I can also choose to build a more complex wave field over the cans, focusing on three points at the same time," says Lerosey.

Ghostly sounds

This technique concentrates the acoustic waves on a spot one-quarter the size of the diffraction limit. To focus the sound even tighter, the team needed to counteract the energy losses incurred as the waves pass through the cans. This is done by amplifying the frequencies that are lost, thus creating signals that build up and cancel out more precisely. These ghostly sounds, like a chime struck in the distance that makes a sheet of metal shake nearby, focus on spots not much bigger than the mouth of a can – about a 12th of the diffraction limit.

"I am especially impressed by their experimental set-up. It’s simple and neat," says Jie Zhu of the University of California, Berkeley. "Yet, their experimentally demonstrated results are clear and straightforward."

Nicholas Fang of the Massachusetts Institute of Technology in Cambridge calls the new approach for focusing sound "exciting". He believes it could be applied to ultrasound frequencies by using smaller resonators. "Such an effect could be useful for applications such as cell sorting in biomedical fields and particle removal in ultrasound cleaning, as well as other interesting actuators," he explains.

Moving with sound

Acoustic actuators harness sound waves to physically move objects, and Lerosey points out that the acoustic field generated by the cans is not only more precise than an ordinarily focused field, it is also stronger. He also suggests that the technique could be extended to focusing waves in elastic materials. But on a fundamental level, Lerosey says this new strategy "gives you the possibility to manipulate sound in new ways that have never been achieved before".

2011年6月16日 星期四

Some hardcore carnivores have a hard time finding meat alternatives such as soy protein or tofu burgers to be palatable. But non-meat eaters may lose their appetite along with their carnivorous friends over this one – a meat alternative made from HUMAN EXCREMENT. Yep, you heard me correctly — Japanese scientist Mitsuyuki Ikeda has developed a “burger” made from soya, steak sauce essence, and protein extracted from human feces. Hit the break for a video explaining the process!

The meat packing industry causes 18 percent of our greenhouse gas emissions, mostly due to the release of methane from animals. The livestock industry also consumes huge amounts of feed and water in relation to the amount of meat that it yields, and many find the industry to be inhumane and cruel to animals. These factors alone are reason enough for vegetarians to replace their meat intake with vegetable proteins and legumes. But Ikeda, a scientist at the Environmental Assessment Center in Okayama, sought to further the field of alternative proteins by recycling a form of protein-rich waste : sewage mud.

“Sewage mud” is exactly what you think it is – poop. Ikeda’s process begins by extracting protein and lipids from the “mud.” The lipids are then combined with a reaction enhancer, then whipped into “meat” in an exploder. Ikeda then makes the poop more savory, by adding soya and steak sauce.

Currently, the price of the poop burgers are 10-20 times that of regular meat, due to the cost of research, but he feels they will even out in a few years. He admits that “some people” may have a psychological aversion to eating artificial meat made of their own poop at first, but thinks many would be open to personally completing the food chain. He also notes that the burgers are extremely low in fat.

While, for the rest of us, it’s hard to believe that any consumers will take a bite out of a poop-sandwich, doing some googling, one will find that there is a long history of the Japanese eating shit (for heath!).

For the iGem competition 2010, a research team out of the Chinese University of Hong Kong has found a way to do data encryption and storage with bacteria. "We harness the incredible adaptability of simple organisms in the tortured environment to make sure that the message stored can be left undisturbed regardless of any environmental changes". The team successes in storing 931,322GB of data in 1g of E. coli, compare to the data density of 14GB/gram for a typical hard disk.